Density functional theory modeling and monte carlo simulation assessment of N-substituted quinoxaline derivatives as mild steel corrosion inhibitors in acidic medium

This work attempts to correlate the structural and electronic properties,such as homo,lumo energy values,frontier orbital energy gap,molecular dipole moment (μ),electron affinity (a),ionization potential (i),electronegativity (χ),global hardness (η),softness (σ),the fraction of electron transferred (δn),electrophilicity index (ω),back-donation (δeback-donation) and mulliken charges using density functional theory (dft) at the b3lyp/6-31g(d,p) basis set,with the inhibitive action of two quinoxaline derivatives named: 3-methyl-1-prop-2-ynylquinoxalin-2(1h)-one (pr-n-q=o) and 3-methyl-1-prop-2-ynylquinoxaline-2(1h)-thione (pr-n-q=s),of the mild steel corrosion in molar hydrochloric acid. monte carlo simulations were further performed to simulate the adsorption of the two quinoxaline derivatives on fe (111) surface in the presence of water and the results show that pr-n-q=s is the most effective as corrosion inhibitor for mild steel in 1 m hcl medium.